(1. 長安大學(xué) 材料科學(xué)與工程學(xué)院，西安 710064；
2. Waikato Centre for Advanced Materials and Manufacturing, University of Waikato, Hamilton 3240, New Zealand)
摘 要: 本研究設(shè)計(jì)了一種低成本短流程粉末冶金固結(jié)與加工技術(shù)制備了亞穩(wěn)β型Ti-5553合金，主要包括快速粉末熱壓、單道次鍛壓和簡單退火熱處理。研究揭示了合金在加工過程中的組織演變機(jī)理、力學(xué)性能優(yōu)化機(jī)理和組織性能關(guān)系。結(jié)果表明：經(jīng)過在1275 ℃流動(dòng)氬氣氣氛環(huán)境的快速熱壓，所得固結(jié)態(tài)合金相對密度高、宏微觀組織均勻，無明顯缺陷。經(jīng)過單道次鍛壓及快速退火處理后，合金的微觀組織和力學(xué)性能得以調(diào)控和優(yōu)化，其微觀組織和力學(xué)性能都對熱處理溫度的變化有較高的敏感性。當(dāng)熱處理溫度為700 ℃和750 ℃時(shí)，合金展現(xiàn)出良好的強(qiáng)塑性匹配，抗拉強(qiáng)度和伸長率分別為1335 MPa和6.6%、1215 MPa和7.2%，原因是多級析出相的組織結(jié)構(gòu)可同時(shí)穩(wěn)固合金的力學(xué)性能強(qiáng)化效果、提高合金的均勻協(xié)調(diào)變形能力，使合金具有高強(qiáng)度和可接受的塑性。
關(guān)鍵字: 粉末冶金；亞穩(wěn)β型鈦合金；低成本；熱加工；微觀組織
（1. School of Materials Science and Engineering, Chang’an University, Xi’an 710064, China;
2. Waikato Centre for Advanced Materials and Manufacturing, University of Waikato, Hamilton 3240, New Zealand）
Abstract:A fast and cost-affordable processing route has been designed to manufacture powder metallurgy metastable β titanium alloy Ti-5553, containing rapid powder consolidation, one-step thermomechanical processing and fast heat treatment. Microstructure evolution mechanism, property optimization mechanism and microstructure-property relationship of the alloy during whole processing route were uncovered and elucidated thoroughly. The results show that the homogeneous macrostructure with high relative density but without obvious defects is achieved for the alloy after thermomechanical powder consolidation. The microstructure and mechanical properties of the processed alloy show high sensitivity to the heat treatment temperature. Specifically, the microstructural regulating and mechanical property optimization are successfully realized after one-step forging and fast annealing for one hour, with satisfactory strength(YS)-ductility(εf) combinations of 1335 MPa and 6.6% at 700 ℃, and 1215 MPa and 7.2% at 750 ℃, respectively. It is deduced that the hierarchical precipitation structure can stabilize the strengthening effect and improve the compatible deformation ability, which is beneficial for the concurrent high strength and moderate ductility.
Key words: powder metallurgy; metastable β titanium alloy; cost-effective; thermomechanical processing; microstructure
